JP2002125388A - Motor driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor driver which can gradually adjust noise mask time and position detection time, according to the rotational speed of a brushless motor. SOLUTION: A circuit for generating a noise mask signal for removing the counter noise from a rectangular wave signal, obtained by comparing the induced voltage of the coil of a motor with the midpoint voltage generates analogous triangular wave signals L1 and L2 which are different in frequency, according to the number of revolutions of the motor. The motor driver determines a reference current value Is=Ip/n, by dividing the amplitude Ip of the triangular signals L1 and L2, after the voltage-to-current conversion of these triangular wave signals S1 and S2 into n:1, and generates a noise mask signal, by comparing the triangular wave signals L1 and L2 with a reference current value Is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driver for driving a brushless motor.

[0002]

2. Description of the Related Art As a motor driver for driving a brushless motor used for rotating a cylinder of a video tape recorder or a spindle of a floppy disk drive, a sensorless motor driver which does not use a phase detection sensor such as a Hall element is used. Used.

In a conventional sensorless motor driver, as shown in FIG. 1, a switching operation is performed so that a waveform of a current flowing through each coil of the brushless motor becomes a rectangular wave energized with a phase of 120 °. During the phase of 60 °), the rotational position of the rotor of the motor is detected.
However, such a motor driver of the rectangular wave 120 ° conduction switching method has a problem that the motor generates noise when the motor rotates. Further, in such a switching method, since the current flowing through the motor changes abruptly, as shown in FIG. 2, the moment when the energization is switched on and off (or the moment when the polarity of the energized current is switched).
In this case, noise due to the back electromotive force of the coil (hereinafter referred to as "back electromotive noise") is generated, and the noise rides on the position detection signal of the motor.

In order to solve such a problem, there is a motor driver of a 150 ° conduction type in which a waveform of a current flowing through a coil has an inclination. In this 150 ° conduction method, FIG.
(Note that the dashed line indicates the waveform of the 120-degree conduction method.) As shown in FIG. 10, a current is smoothly passed through the coil at a phase of 150 °, and the rotational position of the rotor of the brushless motor is shifted at a phase of 30 °. Detected. In such a 150 ° energization method, the current flowing through the coil changes smoothly due to the slope change portion, so that the noise of the motor during motor rotation is reduced. However, the noise reduction is limited, and the noise during motor rotation is limited. If you want to reduce noise, you can't.
Also, in the 150 ° conduction method, as shown in FIG. 4, counter-emergence noise is generated when the brushless motor rotates.
Since the change of the current at the time of energization is reduced, the back electromotive noise is reduced as compared with the 120 ° energization switching method. However, there was no change in the point that the rotation of the motor became unstable due to the back electromotive noise.

As a countermeasure against the noise, there is a method of generating a noise mask signal so as to prevent the back electromotive noise of the coil from passing through. Since the back electromotive noise is generated at the moment when the energization is switched on and off (or at the moment when the polarity of the energization current is switched), in the noise mask method, as shown in FIG. 5, the noise mask signal is generated in accordance with the timing. During the period in which the noise mask signal is generated (hereinafter, referred to as a noise mask period), counter-electromotive noise is prevented from being transmitted to the drive signal synthesis circuit that controls the current supplied to each coil. Since the timing of noise generation can be specified by the output signal from the drive signal synthesis circuit that controls the current flowing through each coil, the mask signal generation circuit charges and discharges the capacitor, detects the charge / discharge voltage with a comparator, and uses the capacitor. The noise mask period of the noise mask signal is determined by utilizing the time required for charging and discharging in the step (a).

That is, assuming that the charge / discharge voltage of the capacitor charged / discharged with the rotation of the rotor changes in a triangular waveform as shown in FIG. 6 (a), the comparator compares the reference voltage Vs with a constant level. Then, as shown in FIG. 6B, a low-level mask signal is generated in a section where the charge / discharge voltage is higher than the reference voltage Vs. Therefore, in such a system, as the rotation speed of the motor increases, the noise mask time decreases accordingly, but the position detection time between the noise mask signals is constant regardless of the rotation speed of the motor. I was

However, when the rotation speed of the motor increases, the period of the triangular wave charge / discharge voltage waveform becomes shorter as shown in FIG. 6C, and accordingly, the noise mask period becomes longer as shown in FIG. It became shorter gradually, and as a result, the back electromotive noise could not be removed, and the rotation of the motor became unstable.

In order to solve these problems, the reference voltage Vs for comparing the charge / discharge voltage should be reduced to make the noise mask time sufficiently long. There is a problem that the detection period for detecting the rotational position of the rotor is shortened, and the rotational position of the rotor cannot be detected, so that the brushless motor cannot be driven.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention has been made in view of the above prior art, and an object of the present invention is to gradually reduce a noise mask time and a position detection time according to the rotation speed of a brushless motor. It is an object of the present invention to provide a motor driver which can be adjusted to a predetermined value.

The motor driver according to the present invention includes a means for generating a signal synchronized with the rotation of the motor by comparing an induced voltage generated in a coil of the motor with a predetermined threshold value, and a means for synchronizing the motor with a noise mask signal. A motor driver comprising: a noise mask unit that removes noise included therein; and a unit that supplies a current to a motor coil based on the synchronization signal from which the noise has been removed by the noise mask unit. Means for generating a similar triangular wave signal whose frequency increases in accordance with the noise mask signal by increasing or decreasing a reference value in accordance with an increase or decrease in the amplitude of the triangular wave signal, and comparing the reference value with the triangular wave signal. And means for generating Note that the triangular wave signal here does not need to be a strict triangular wave, but also includes a partially missing signal, for example, a trapezoidal wave.

According to the motor driver of the present invention, the noise mask time and the position detection time can be gently changed according to the number of rotations of the motor, so that noise can be reduced. Further, even when the number of rotations of the motor increases, the risk of the noise mask time being sharply shortened and the back electromotive noise being unable to be removed is reduced, so that the rotation of the motor can be stabilized.

According to the embodiment of the present invention, since the reference value used in the means for generating the noise mask signal is kept at a constant ratio with respect to the amplitude of the triangular wave signal, the reference value can be obtained by a simple calculation. The value is obtained, and the reference value can be increased or decreased according to the increase or decrease of the amplitude of the triangular wave signal.

According to another embodiment of the present invention, in the means for generating the synchronization signal, the threshold value to be compared with the induced voltage of each phase has a common value between the phases. . Therefore, it is possible to eliminate variations between the phases in the synchronization signal and to stabilize the rotation of the motor.

According to another embodiment of the present invention, in a motor driver according to the present invention in which a current supplied to a coil of a motor has a slope change portion, the coil current has a slope change portion. The gradient is set to decrease as the rotation speed of the motor decreases.
Even if a slope change portion is provided to gradually change the coil current, if the slope of the slope change portion is constant regardless of the number of rotations of the motor, as the rotation of the motor slows down, the slope change The gradient of the portion becomes relatively steep, and the waveform approaches a rectangular wave, which may increase the noise of the motor. In this embodiment, when the rotational speed of the motor decreases, the slope change portion is changed so as to be relatively gentle. Therefore, even if the rotational speed of the motor decreases, noise can be reduced.

Another motor driver according to the present invention includes a means for generating a signal synchronized with the rotation of the motor by comparing an induced voltage generated in a coil of the motor with a predetermined threshold value, Means for generating a triangular wave signal, the rate of change of which increases with the frequency according to, a means for generating a noise mask signal by comparing the triangular wave signal with a predetermined reference value, and A noise mask unit for removing noise included in the synchronization unit; and a unit for supplying a current to a motor coil based on the synchronization signal from which noise has been removed by the noise mask unit.

According to another motor driver of the present invention,
Since the noise mask time and the position detection time can be gently changed according to the number of rotations of the motor, noise can be reduced. Further, even when the number of rotations of the motor increases, the risk of the noise mask time being sharply shortened and the back electromotive noise being unable to be removed is reduced, so that the rotation of the motor can be stabilized.

The components described above of the present invention can be combined as much as possible.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 7 is a block circuit diagram of a sensorless motor driver 1 for a brushless motor according to one embodiment of the present invention, and FIG. 11 shows waveforms at various points in the block circuit diagram of FIG. In the motor driver 1, the brushless motor 3 is obtained by extracting the back electromotive force VU, VV, VW generated in the coils 4, 5, and 6 provided in the U, V, and W phases of the brushless motor 3, respectively. The rotation position of the third rotor is detected. This coil 4,
The back electromotive forces VU, VV, VW of 5 and 6 are shown in FIG.
(B) It has a waveform as shown in (c), and contains counter-electromotive noise.

The comparator circuit 2 comprises three comparators 21, 22, 23 as shown in the block circuit diagram of FIG.
And the back electromotive force VU, VV, VW is set to the midpoint voltage V
N, respectively, to obtain square wave signals PU, P
V and PW are generated. That is, three comparators 2
Back electromotive forces VU, VV, VW are input to the non-inverting input terminals 1, 22, and 23, respectively, and a common midpoint voltage VN is input to each inverting input terminal. The midpoint voltage VN is taken out from the midpoint of the three star-connected resistors 24, 25, and 26 constituting the midpoint voltage generation unit 27, and the other end of each of the resistors 24, 25, and 26 has a counter electromotive force. Power V
U, VV, and VW are input. The common midpoint voltage VN generated in this manner is shown in FIGS.
It has a waveform as shown in FIG. The rectangular wave signals PU, P output from the comparators 21, 22, 23
V and PW have waveforms as shown in FIGS. 11 (d), (e) and (f), and also include counter-electromotive noise.

Conventionally, in a comparator circuit, FIG.
As shown in FIG. 2, each comparator 21, 22, and 23
Since the output voltages VU, VV, VW of the phase, the V phase, and the W phase were compared with the reference voltage of each phase, the variation between the phases was large. On the other hand, in the comparator circuit 2 according to the embodiment of the present invention, as shown in FIG. 8, each of the comparators 21, 22, and 23 has a reference voltage for comparison.
The midpoint voltage VN corresponding to the midpoint voltage of the motor is generated inside the comparator circuit 2 and is shared by the three phases as a common reference voltage. Can be. The reference voltage may have a hysteresis.

Next, each of the comparators 21, 22, 23
Are output to the mask circuit 28. The mask circuit 28 performs a masking process on the rectangular wave signals PU, PV, and PW using the noise mask signal Vm generated by the mask signal generation circuit 9 described later to remove the counter-electromotive noise (FIGS. 11G and 11H). The rectangular wave signals QU, QV, and QW having the waveforms as shown in (i) are output to the position detection signal generator 32 and the FG signal generator 33.

The mask circuit 28 has a noise mask signal Vm
Is low level, the square wave signals PU, PV, PW
And the signals PU, PV, and PW are passed when the noise mask signal Vm is at a high level. As a result, the rectangular wave signals QU, QV, and QW from which noise has been removed are input to the position detection signal generator 32 and the FG signal generator 33.

The position detection signal generator 32 generates position detection signals IA to IL based on the rectangular wave signals QU, QV, and QW, and outputs the position detection signals IA to IL to the drive signal synthesis circuit 10. . Position detection signals IA to IL
Changes according to the change in the motor rotational position (phase), and has a waveform as shown in FIG.

The FG signal generation section 33 generates an FG signal and outputs the FG signal to the triangular wave generation circuit 7.
The FG signal is generated from the signals QU, QV, QW after the back electromotive noise has been removed from the square wave signals PU, PV, PW, and becomes high and low when any of the signals QU, QV, QW is inverted. Invert operation. The FG signal indicates the rotation speed of the brushless motor 3 and is shown in FIG.
It is used in a servo mechanism (not shown) provided for keeping the rotation speed of the motor 3 stable.

The triangular wave generation circuit 7 generates two triangular wave signals SL1 and SL2 based on the FG signal. The triangular wave generation circuit 7 includes two charge / discharge circuits 3 each including two constant current sources 37 and 39, a capacitor 38, and a switch.
6 is provided. In these charge / discharge circuits 36, a constant current source 37 (current value I) and a capacitor 38 as shown in FIG.
Are connected in series, and the constant current source 39 (current value 2
What connects I) and the switch 40 in series is connected in parallel with the capacitor 38. Then switch 40
Is open, the upper end voltage V of the capacitor 38
Increases linearly as V = (It / C) + constant. Conversely, in the discharging state in which the switch 40 is closed, the upper end voltage V of the capacitor 38 decreases linearly as V = {(I−2I) t / C} + constant− (It / C) + constant. Here, C is a capacitor 38
And t is time. Therefore, a triangular wave signal is output from the upper end of the capacitor 38 by opening and closing the switch 40 at a constant cycle.

The switch 40 is constituted by a switching transistor or the like. In the charging / discharging circuit 36, when the FG signal is high, the switch 40 is opened and when the FG signal is low, the switch 40 is closed, as shown in FIG. The triangular wave signal SL1 is output. The other charge / discharge circuit 3
In 6, the switch 40 is closed when the FG signal is high and the switch 40 is opened when the signal is low, thereby outputting a triangular wave signal SL2 as shown in FIG.

Therefore, the two triangular wave signals SL1 and SL2 output from the triangular wave generating circuit 7 are shown in FIG.
The waveform is as shown in FIG.
The phase is reversed. Also, the triangular wave signals SL1, S
The period of L2 becomes shorter when the rotation speed of the motor becomes higher and the period of the FG signal becomes shorter. However, even if the cycle changes, the cycle of the voltage changes while the rate of change of the voltage remains constant and similar waveforms (see FIG. 10; however, FIG. 10 is converted to a current waveform).

From the triangular wave generation circuit 7, a triangular wave signal SL
1 and SL2 are output as voltage signals, and the triangular wave signals SL1 and SL2 are
After being converted to L2, it is sent out to the drive signal synthesis circuit 10 and the mask signal generation circuit 9.

When the mask signal generation circuit 9 receives the triangular wave (current) signals L 1 and L 2 from the V / I conversion circuit 8,
A reference current value Is is generated from the triangular wave signals L1 and L2. As shown in FIG. 10, the reference current value Is is a peak-to-peak value of the triangular wave signal L1 or L2.
peak) obtained by dividing the current value (amplitude) Ip at a predetermined ratio n: 1. That is, Is = Ip / n (n
Is a positive real number). Next, the triangular wave signals L1 and L2
Is compared with the reference current value Is. If any one of the triangular wave signal L1 and the triangular wave signal L2 is larger than the reference current value Is, the noise mask signal Vm is set to low and the triangular wave signal L
If both 1 and the triangular wave signal L2 are smaller than the reference current value Is, the noise mask signal Vm is set to high. As a result, a noise mask signal Vm having a waveform as shown in FIG. 11 (n) is obtained, and FIG. 11 (d) (e) (f) and FIG.
As can be seen by comparing (n), the noise mask signal V
m is low at the same timing as when the back electromotive noise occurs. The noise mask signal Vm is used for removing the counter electromotive noise in the comparator circuit 2 as described above.

In the mask signal generation circuit 9, since the reference current value Is is changed so as to be proportional to the peak-to-peak value Vp of the triangular wave signals L1 and L2, the noise mask time and the position detection time (noise mask time) And the time between the noise mask time) change in accordance with the rotation speed of the motor. Moreover, as compared with the conventional case where the reference voltage Vs is constant, the noise mask time changes more gently according to the rotation speed of the motor than the conventional case. In addition, even when the number of rotations of the motor increases, the noise mask time does not suddenly become shorter, and the possibility that the noise mask time becomes shorter than the width of the back electromotive noise is reduced.

The drive signal synthesizing circuit 10 combines the position detection signals IA to IL with the triangular wave signals L1 and L2 to generate the signals shown in FIGS. 11 (o), (p), (q), (r) and (s).
(T) drive signals DUU, DVU, DWU,
DUL, DVL, and DWL are combined and output.

The current supply means 11 is composed of six power transistors T1 to T6, and each of the power transistors T1 to T6 has drive signals DUU, DUL, D
ON / OFF by VU, DVL, DWU, DWL
Controlled off.

The collector of the NPN power transistor T1 is connected to the positive electrode of the battery 12, and the emitter is connected to the collector of the NPN power transistor T2. The drive signal DUU is input to the base of the power transistor T1. The emitter of the power transistor T2 is a resistor 2
The drive signal DUL is input to the base via a drive signal DUL. And the power transistor T
The connection midpoint between 1 and T2 is connected to the U-phase coil 4 of the brushless motor 3 via the terminal of the current supply means 11.

Similarly, an NPN power transistor T3
Is connected to the positive electrode of the battery 12 and the emitter is N
Connected to the collector of PN type power transistor T4. The drive signal DVU is input to the base of the power transistor T3. The emitter of the power transistor T4 is connected to the ground via the resistor 29, and the drive signal DVL is input to the base. The connection midpoint between the power transistors T3 and T4 is connected to the V-phase coil 5 of the brushless motor 3 via the terminal of the current supply means 11.

Similarly, an NPN power transistor T5
Is connected to the positive electrode of the battery 12 and the emitter is N
Connected to the collector of PN type power transistor T6. The drive signal DWU is input to the base of the power transistor T5. The emitter of the power transistor T6 is connected to the ground via the resistor 29, and the drive signal DWL is input to the base. The midpoint of connection between the power transistors T5 and T6 is connected to the W-phase coil 6 of the brushless motor 3 via the terminal of the current supply means 11.

As a result, the drive signals DUU, DVU,
The current supply means 11 driven by the DWU, DUL, DVL, and DWL supplies the U-phase coil 4, the V-phase coil 5, and the W-phase coil 6 of the brushless motor 3 respectively as shown in FIG.
(U), (v) and (w), a U-phase current, a V-phase current, and a W-phase current that do not include noise are supplied by, for example, a 150 ° conduction method. The triangular wave signals L1 and L2 output from the V / I conversion circuit 8 to the drive signal synthesis circuit 10 are shown in FIG.
1 (u) (v) (w) determines the slope of the slope change portion in the U-phase current, V-phase current, and W-phase current. According to the triangular wave signals LA and L2 having small slopes, the U-phase current, V The slope of the slope change portion in the phase current and the W-phase current is also reduced, and the motor noise is also reduced.

Further, in the embodiment of the present invention, the noise mask time and the position detection time can be gently changed according to the motor rotation speed as described above. It can also be used in the case of an energization method, and a silent motor with less noise can be manufactured.

(Second Embodiment) FIG. 15 is a diagram showing a configuration of a charge / discharge circuit 41 used in a triangular wave generation circuit according to another embodiment of the present invention. In the first embodiment, the charge / discharge circuit is charged / discharged at a constant current value.
In the second embodiment, the current values I, 2I of the constant current sources 37, 39 for charging / discharging the current to the charge / discharge circuit 41 are changed according to the rotation speed of the motor 3. That is,
The number of rotations of the motor 3 is determined based on the FG signal.
When the rotation speed of the motor 3 increases, the current values I and 2I increase, and when the rotation speed of the motor 3 decreases, the current values I and 2I decrease.

As a result, when the number of rotations of the motor 3 is low, as shown in FIGS.
1, the change in SL2 is gradual, but when the rotation speed of the motor 3 increases, the change in the triangular wave signals SL1, SL2 becomes steep. As a result, the reference current value Is remains unchanged (constant).
However, both the noise mask time and the position detection time change according to the number of rotations of the motor 3, and the change in the noise mask time becomes more gradual than in the past. Therefore, also in this method, the same operation and effect as in the first embodiment can be obtained.

(Third Embodiment) In the motor driver described in the first embodiment, the drive signals DUU, DUU,
Since DVU, DWU, DUL, DVL, and DWL are combined, the frequency of the triangular wave signals L1 and L2 changes depending on whether the rotation speed of the motor is high or low. , The same slope as the triangular wave signals L1 and L2). For this reason, when the rotational speed of the motor decreases, the gradient of the gradient change portion such as the U-phase current flowing through each of the coils 4, 5, and 6 of the motor becomes relatively large and approaches a rectangular wave. That is, FIG. 17A shows a waveform of a U-phase current or the like flowing through the coils 4, 5, and 6 when the rotation speed is high, and FIG. The waveform of the U-phase current and the like flowing through 6 is shown. As can be seen from this, the waveform of the U-phase current and the like has a larger period when the rotation speed of the motor decreases, but the gradient of the gradient change portion is the same. Therefore, FIG.
FIG. 17 shows the coil current waveform of FIG.
17 (a), the waveform of FIG. 17 (c) is closer to a rectangular wave than the waveform when the number of rotations is large as shown in FIG. 17 (a). You can see that it is. As a result, the noise of the motor 3 may increase.

Therefore, in the third embodiment, FIG.
As can be seen by comparing (a) and (c), when the rotation speed of the motor 3 decreases, the triangular wave signals L1, L2
Is made to be small. As a result, even if the rotation speed of the motor 3 decreases, the triangular wave signal L
1, since the inclination of the inclination change portion of L2 becomes small, FIG.
8 (b) and 8 (d), each coil 4, 5,
6, the slope of the slope change portion of the U-phase current, the V-phase current, and the W-phase current becomes gentle, and even if the motor speed changes, the similarity of these current waveforms increases, and the noise of the motor 3 increases. Can be alleviated.

[0042]

According to the motor driver of the present invention, the noise mask time and the position detection time can be gently changed in accordance with the rotation speed of the motor. The risk that the mask time is rapidly shortened and the back electromotive noise cannot be removed is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing three-phase waveforms in a conventional 120 ° conduction system.

FIG. 2 is a diagram showing counter-emergence noise generated in a three-phase waveform in the above-mentioned 120 ° conduction method.

FIG. 3 is a diagram showing three-phase waveforms in a conventional 150 ° conduction method.

FIG. 4 is a diagram showing counter-electromotive noise generated in a three-phase waveform in the 150 ° conduction method according to the first embodiment.

FIG. 5 is a diagram illustrating a relationship between a back electromotive noise generated in a three-phase waveform and a noise mask signal.

6 (a) and 6 (b) are diagrams showing a constant current charging / discharging waveform and a mask signal when the motor rotation speed is low, and FIGS. 6 (c) and 6 (d) are constant current charging / discharging when the motor rotation speed is high. FIG. 3 is a diagram illustrating a waveform and a mask signal.

FIG. 7 is a block circuit diagram showing a configuration of a motor driver according to an embodiment of the present invention.

8 is a block circuit diagram showing a configuration of a comparator circuit in the block circuit diagram of FIG. 7;

FIG. 9 is a diagram illustrating an example of a charge / discharge circuit in the triangular wave generation circuit.

10 (a) and 10 (b) are diagrams showing a constant current charge / discharge waveform and a mask signal when the motor speed of the motor driver in FIG. 7 is low, and FIGS. 10 (c) and (d) are diagrams in which the motor speed is high. FIG. 6 is a diagram showing a constant current charge / discharge waveform and a mask signal at the time.

11 (a) to 11 (w) are diagrams showing waveforms of respective parts in the block circuit diagram of the motor driver of FIG. 7;

FIG. 12 is a diagram illustrating a configuration of a conventional comparator.

FIG. 13 is a diagram showing three-phase waveforms in a 165 ° conduction method.

FIG. 14 is a diagram showing counter-electromotive noise generated in a three-phase waveform in the 165 ° conduction method.

FIG. 15 is a diagram showing a configuration of a charge / discharge circuit according to another embodiment of the present invention.

FIGS. 16A and 16B are diagrams showing a constant current charge / discharge waveform and a mask signal when the rotation speed of the motor is low in the above embodiment, and FIGS. 16C and 16D are diagrams when the rotation speed of the motor is high. FIG. 3 is a diagram showing a constant current charge / discharge waveform and a mask signal.

17A is a waveform diagram showing a U-phase current when the motor rotation speed is high, FIG. 17B is a waveform diagram showing a U-phase current when the motor rotation speed is low, and FIG. FIG. 9 is a diagram showing a waveform when the U-phase current waveform of FIG.

FIGS. 18A and 18B are waveform diagrams showing triangular wave signals L1 and L2 and a U-phase current when the rotation speed of the motor is high, and FIGS.
(D) is a triangular wave signal L1 when the rotation speed of the motor is low,
It is a wave form diagram which shows L2 and U phase current.

[Explanation of symbols]

 2 Comparator circuit 4, 5, 6 Coil 7 Triangular wave generation circuit 8 V / I conversion circuit 9 Mask signal generation circuit 10 Drive signal synthesis circuit 11 Current supply means 28 Mask circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H560 BB04 BB12 DA13 DC13 EB01 EC03 RR10 TT07 TT20 UA02 XA12

Claims (5)

[Claims] A means for generating a signal synchronized with rotation of the motor by comparing an induced voltage generated in a coil of the motor with a predetermined threshold value; and removing a noise included in the synchronization means by a noise mask signal. And a means for supplying a current to a motor coil based on the synchronization signal from which noise has been removed by the noise mask means, wherein the frequency increases in accordance with an increase in the motor rotation speed. A means for generating a similar triangular wave signal, and a means for increasing or decreasing a reference value in accordance with an increase or decrease in the amplitude of the triangular wave signal, and generating the noise mask signal by comparing the reference value with the triangular wave signal. , With a motor driver. 2. The motor driver according to claim 1, wherein the reference value used in the means for generating the noise mask signal is maintained at a constant ratio with respect to the amplitude of the triangular wave signal. 3. In the means for generating the synchronization signal,
The motor driver according to claim 1, wherein the threshold value compared with the induced voltage of each phase has a common value between the phases. 4. The motor driver according to claim 1, wherein the current supplied to the coil of the motor has a slope change portion. The gradient of the slope change portion of the coil current is such that the rotation speed of the motor is low. A motor driver that gets smaller as it goes. 5. A means for generating a signal synchronized with the rotation of the motor by comparing an induced voltage generated in a coil of the motor with a predetermined threshold value. Means for generating a triangular wave signal, which increases the rate of change, means for generating a noise mask signal by comparing the triangular wave signal with a predetermined reference value, and noise included in the synchronization means based on the noise mask signal. A motor driver comprising: noise mask means for removing; and means for supplying a current to a coil of a motor based on the synchronization signal from which noise has been removed by the noise mask means.